1. Network Designs

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3. Objectives Understand why various networking topologies are used
Variations of standard networking topologies
Deciding from the products required to determine the best network topology the environment. `
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4. Network Design Good network design includes:
Analyzing network requirement
Selecting a network topology
Selecting equipment to fit that topology
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5. Designing a Network Layout
Topology refers to physical layout including computers, cables, and other resources
Determines how components communicate
Basic network design is referred to as topology, layout, diagram, and map
Discuss the reasons why the topology of a network is important. Emphasize how the logical topology can dictate the type of equipment needed.
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6. The Standards with Topologies
Three common topologies:
Bus- A single cable connection, all nodes are connected to one central node that routes all data passing to and from them.
Star- Computers are connected through a central point, called a hub.
Ring- Data are passed round the ring in one direction only, like a loop.
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7. Bus The bus topology is the easiest to manager.
Data on a star network always passes through the hub, switch, or concentrator before continuing to its destination.
Components connect via backbone or single cable segment
If the cable break data can not be processed, the network fails.
Bus- A single cable connection, all nodes are connected to one central node that routes all data passing to and from themDue to the nature of signal travel, computers listen to each other for transmitting and sending information.
ii. Network performance slows as more computers are placed on the bus
iii. Computers only listen for data being sent; not responsible for moving data to next computer. Failure of one computer has no effect on rest of network.
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8. Bus Topology Network 8 Copyright Texas Education Agency (TEA)
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9. Bus Communications
In bus topology, only one computer can send information at a time
Bus is a passive topology
The computers on the network simply listen and receive the signal, they don’t amplify the signal in any way.
In active topology, computers are responsible for sending the data along the network.
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10. Bus Communication Continued
A non-terminated signal that continues to navigate the network, travels across the medium, a signal transmits to both ends of any bus.
During a bus communication cable termination, a terminator is attached that prevents a signal from bouncing.
A failure of communication can occur when the cable is cut or disconnected.
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11. Terminated Bus Network
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12. Star Topology
In today’s networks the star topology has become the dominant topology.
Another major topology which the computers connect via a central connecting point
Requires more cable and has single point of failure
Star- Computers are connected through a central point, called a hub.
. If the hub fails, network is down, but failure of single computer or cable does not affect network
Explain that many homes networks have star topologies.
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14. Ring Topology
Data that is passed round the ring in one direction only, like a loop.
May be physically wired as a star with central hub passing token in a circle
Ring- Data are passed round the ring in one direction only, like a loop. Computers attached in a circle with no termination necessary.
A ring network has something called a Fiber Distributed Data Interface (FDDI),
One computer failing can bring down single-ring network unless it has smart hub that automatically removes failed computer from ring
Discuss the term “active topology” and FDDI.. Active Topology- A network topology which the computers are responsible for sending the data along the network. Explain that rings are considered active because every computer is responsible for retransmitting the token or data.
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16. Ring Network
Wired-like star networked topology device, which handles traffic like a ring
Fiber Distributed Data Interface (FDDI)
When one ring fails, dual ring network uses secondary ring and continues to work
Shares network resources equally
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17. Wireless Topologies Eliminate cables
Wireless LANs use centralized device similar to hub to control communication
Use star topology
Signals travel through one central device
Explain why wireless topologies are considered to use a star topology. Wireless networks are made up of transmitters that broadcast packets using radio frequencies.
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18. Hubs May be active or passive
Downside of an active hub it require a cable bandwidth shared among connected stations.
Passive hub no electrical power is required. A simply central connection point, with no amplification or regeneration.
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19. Lesson Summary Networks build upon one of three basic topologies
Hub, a central point of concentration for star network, passes electronic signals to network
Network layout should be consistent with existing network and accurately maintained as network changes
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